Well, frankly, because it's just dthrow -> c4 stick...something mentioned long ago back when Snake's metagame was still developing. Then we realized it was difficult to execute the C4 stick on someone after dthrow unless they just lay there on the ground for an extended amount of time, which is largely unreliable. Especially if they do a get-up attack during which the shield stun will likely prevent you from being able to plant the C4 in the first place.
Also, there are much better options out of dthrow than attempting to plant a C4. Whereas if you do plant one, an experienced opponent will dodge/shield immediately as soon as they hear the "Now!" unless you give them enough hitstun. This could potentially work to your advantage if you force them to shield and you're nearby, since detonating the C4 while you're in the air seems to leave very little lag animation as soon as you land, during which you can punish the shield/spot-dodge. Although, this is highly situational and you basically have to be right next to them which can put you in danger.
Once more, attempting to plant a C4 is not as efficient as simply tech chasing and following with more dthrows to rack up more damage. You also get a chance to add some grab attacks in there if they are at a high percentage to remove some of the stale move negation on your other attacks and prep you for that tilt kill. It's actually quite safer and puts you in no immediate danger due to the immobilizing properties of Snake's dthrow.
A large reason that there is little snake tactical discussion is because the majority of that was done long ago. If you were here back then, you'd be swamped to your knees with new developments. However, that is not the case as of this day when the majority of Snake's metagame has been discovered. Now it's simply discovering synergy between attacks and explosives and it's getting harder and harder to have new developments unless you get extremely creative.
For new Snake players, it probably all seems new and exciting, but unfortunately, chances are it's been done before.
...I guess that's just my reasoning...and I've kinda quit competitive brawl lol.